(1) Field of the Invention
The present invention relates to an improved sealing assembly for refrigerator cabinets and the like with a profile made of plastic material.
(2) Description of Related Art
It is known from the Italian Patent No. 1281660 held by the present applicant, a profile made of plastic material for refrigerator cabinets and the like, where the said refrigerator cabinets are equipped with a door and an inner door panel constrained to the structure, said profile having a bellows-type gasket portion which provides a sealed closing between the door and the cabinet. In this embodiment, the profile and the gasket portion are coupled together or form a single integrated piece produced by co-extrusion of two materials having different degrees of rigidity so as to enable, if necessary, convenient detachment of the gasket portion from the profile along the area of their connection. In addition, the profile has at least one elastically compliant side branch which acts as a spring to connect together by snap action the profile and the inner door panel. In the aforesaid profile, a groove is present which is identified by a pair of walls that extend vertically or obliquely from a base which, in the operative position of coupling, overlaps the door and the inner door panel along their line of coupling.
For its installation, the profile, which carries the co-extruded gasket, is conveniently arranged in the form of a frame and is supplied to the manufacturer of the refrigerator cabinet in this form. As further references to the prior art, the following European patents held by the present applicant may be cited: EP 0 146 994 and EP 0 319 087.
The frame made of the profile is caused to descend, for example by means of an appropriate mechanical arm, towards the inner door panel, which is, for instance, suitably positioned on a support that blocks it in place. As soon as the arm of the side branch comes into contact with the edge of the inner door panel, under the thrust of the said edge it yields and starts to bend elastically inwards like a spring about its own flexible fulcrum. Once the compliant side branch has completed its travel along the edge of the inner door panel and when the said edge has reached the height of the above-mentioned groove, the branch, as a result of its own elastic return, snaps into position engaging the edge of the inner door panel, so blocking the said edge. Insertion of the frame welded on the inner door panel may be achieved with great ease even manually, provided that care is taken to engage first the corners, two at a time, and then complete the insertion in the points of the perimeter where the edge of the inner door panel has not yet completely entered the groove of the side branch.
The profile and the inner door panel thus assembled are then rested on the door (for example, by means of a robotized system), and the entire assembly is blocked by means of foam-injection into the gap between the door and the inner door panel, with functions of thermal insulation.
In the profile in question, the base extends on a single plane or on planes that are slightly staggered with respect to one another. The base terminates laterally with a pair of sealing strips made of a soft material co-extruded together with the rigid material of the profile. The said strips constitute the gaskets containing the foam. In particular, the sealing strip provided to ensure operative sealing on the inner door panel is made in such a way as to compensate for the distance between the base of the profile and the inner door panel itself, between which there remains identified a gap for the elastic return of the engaging tooth of the side branch, and in such a way as to facilitate the movement of engagement of the said branch on the inner door panel. The said sealing strip consequently also has the function of facilitating said movement of the side branch because it maintains the distance between the base of the profile and the inner door panel, leaving free play for said engagement tooth in the useful gap referred to above.
It should in any case be emphasized that leakage of foam along the perimeter of the door is very rare, whereas it is precisely the area of the corners where welding is carried out that proves particularly critical.
It has in fact been noted that in the welded corner, the side branch, which terminates with a grooved seat, must remain elastically mobile in order to guarantee functionality of the profile, and consequently must not be welded. To avoid welding, the side branch must be cut 2–3 mm more than the cutting plane of the entire section of the profile. Albeit preventing the branch from being welded, this solution, in the step of welding of the four sides of the frame, leads to the presence of a 2–3 mm slit along the entire length of the side branch.
If the dimensional tolerances of assembly of the three components making up the door—namely, inner door panel, frame, and steel-metal shell—are not optimal, this slit leads to leakage of foam. In an attempt to prevent such leakage, the slit is closed with adhesive tape by means of an operation that requires time and involves loss of productivity.
The purpose of the present invention is to further improve tightness of the seal to prevent any foam from leaking during the step of foam-injection in a profile of the type referred to.
The above requirement derives from the fact that the parts to be assembled, and in the first place the profile and inner door panel, are manufactured with dimensional tolerances that preferably tend to be increasingly wide.
It should therefore once again be emphasized that the sealing strip that extends from the base of the profile towards the inner door panel, as described in the Italian Patent No. 1281660 referred to previously, proves in practice frequently insufficient to contain the foam when the dimensional tolerances between the door and the inner door panel exceed a certain limit. This is especially true when the foam is injected in the liquid phase according to the system known as “foam chamber” system, the said chamber being closed and inclined on its longer side or on its shorter side. In this case, the liquid pours, in fact, immediately onto the side opposite to the one into which the foam is injected, and the seal between the elastic side branch of the profile and the inner door panel may prove insufficient.
The fact that the foam comes out during the stage of foam injection between the door and the inner door panel may mean damage of an aesthetic nature (the foam that comes out is visible), but, above all, serious functional damage (the foam that leaks through the passages on account of insufficient sealing solidifies and causes serious imbalance in the set of the assembled door-inner door panel system).